244 lines
8.3 KiB
C++
244 lines
8.3 KiB
C++
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/*
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* Copyright (c) 2014 The WebRTC project authors. All Rights Reserved.
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*
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* Use of this source code is governed by a BSD-style license
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* that can be found in the LICENSE file in the root of the source
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* tree. An additional intellectual property rights grant can be found
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* in the file PATENTS. All contributing project authors may
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* be found in the AUTHORS file in the root of the source tree.
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*/
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// Based on the WAV file format documentation at
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// https://ccrma.stanford.edu/courses/422/projects/WaveFormat/ and
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// http://www-mmsp.ece.mcgill.ca/Documents/AudioFormats/WAVE/WAVE.html
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#include "webrtc/common_audio/wav_header.h"
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#include <algorithm>
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#include <cstring>
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#include <limits>
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#include <string>
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#include "webrtc/base/checks.h"
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#include "webrtc/common_audio/include/audio_util.h"
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namespace webrtc {
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namespace {
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struct ChunkHeader {
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uint32_t ID;
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uint32_t Size;
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};
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static_assert(sizeof(ChunkHeader) == 8, "ChunkHeader size");
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// We can't nest this definition in WavHeader, because VS2013 gives an error
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// on sizeof(WavHeader::fmt): "error C2070: 'unknown': illegal sizeof operand".
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struct FmtSubchunk {
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ChunkHeader header;
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uint16_t AudioFormat;
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uint16_t NumChannels;
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uint32_t SampleRate;
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uint32_t ByteRate;
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uint16_t BlockAlign;
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uint16_t BitsPerSample;
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};
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static_assert(sizeof(FmtSubchunk) == 24, "FmtSubchunk size");
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const uint32_t kFmtSubchunkSize = sizeof(FmtSubchunk) - sizeof(ChunkHeader);
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struct WavHeader {
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struct {
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ChunkHeader header;
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uint32_t Format;
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} riff;
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FmtSubchunk fmt;
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struct {
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ChunkHeader header;
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} data;
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};
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static_assert(sizeof(WavHeader) == kWavHeaderSize, "no padding in header");
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} // namespace
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bool CheckWavParameters(size_t num_channels,
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int sample_rate,
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WavFormat format,
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size_t bytes_per_sample,
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size_t num_samples) {
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// num_channels, sample_rate, and bytes_per_sample must be positive, must fit
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// in their respective fields, and their product must fit in the 32-bit
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// ByteRate field.
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if (num_channels == 0 || sample_rate <= 0 || bytes_per_sample == 0)
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return false;
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if (static_cast<uint64_t>(sample_rate) > std::numeric_limits<uint32_t>::max())
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return false;
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if (num_channels > std::numeric_limits<uint16_t>::max())
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return false;
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if (static_cast<uint64_t>(bytes_per_sample) * 8 >
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std::numeric_limits<uint16_t>::max())
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return false;
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if (static_cast<uint64_t>(sample_rate) * num_channels * bytes_per_sample >
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std::numeric_limits<uint32_t>::max())
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return false;
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// format and bytes_per_sample must agree.
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switch (format) {
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case kWavFormatPcm:
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// Other values may be OK, but for now we're conservative:
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if (bytes_per_sample != 1 && bytes_per_sample != 2)
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return false;
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break;
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case kWavFormatALaw:
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case kWavFormatMuLaw:
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if (bytes_per_sample != 1)
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return false;
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break;
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default:
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return false;
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}
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// The number of bytes in the file, not counting the first ChunkHeader, must
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// be less than 2^32; otherwise, the ChunkSize field overflows.
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const size_t header_size = kWavHeaderSize - sizeof(ChunkHeader);
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const size_t max_samples =
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(std::numeric_limits<uint32_t>::max() - header_size) / bytes_per_sample;
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if (num_samples > max_samples)
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return false;
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// Each channel must have the same number of samples.
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if (num_samples % num_channels != 0)
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return false;
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return true;
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}
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#ifdef WEBRTC_ARCH_LITTLE_ENDIAN
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static inline void WriteLE16(uint16_t* f, uint16_t x) { *f = x; }
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static inline void WriteLE32(uint32_t* f, uint32_t x) { *f = x; }
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static inline void WriteFourCC(uint32_t* f, char a, char b, char c, char d) {
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*f = static_cast<uint32_t>(a)
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| static_cast<uint32_t>(b) << 8
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| static_cast<uint32_t>(c) << 16
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| static_cast<uint32_t>(d) << 24;
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}
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static inline uint16_t ReadLE16(uint16_t x) { return x; }
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static inline uint32_t ReadLE32(uint32_t x) { return x; }
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static inline std::string ReadFourCC(uint32_t x) {
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return std::string(reinterpret_cast<char*>(&x), 4);
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}
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#else
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#error "Write be-to-le conversion functions"
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#endif
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static inline uint32_t RiffChunkSize(size_t bytes_in_payload) {
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return static_cast<uint32_t>(
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bytes_in_payload + kWavHeaderSize - sizeof(ChunkHeader));
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}
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static inline uint32_t ByteRate(size_t num_channels, int sample_rate,
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size_t bytes_per_sample) {
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return static_cast<uint32_t>(num_channels * sample_rate * bytes_per_sample);
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}
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static inline uint16_t BlockAlign(size_t num_channels,
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size_t bytes_per_sample) {
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return static_cast<uint16_t>(num_channels * bytes_per_sample);
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}
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void WriteWavHeader(uint8_t* buf,
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size_t num_channels,
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int sample_rate,
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WavFormat format,
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size_t bytes_per_sample,
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size_t num_samples) {
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RTC_CHECK(CheckWavParameters(num_channels, sample_rate, format,
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bytes_per_sample, num_samples));
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WavHeader header;
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const size_t bytes_in_payload = bytes_per_sample * num_samples;
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WriteFourCC(&header.riff.header.ID, 'R', 'I', 'F', 'F');
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WriteLE32(&header.riff.header.Size, RiffChunkSize(bytes_in_payload));
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WriteFourCC(&header.riff.Format, 'W', 'A', 'V', 'E');
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WriteFourCC(&header.fmt.header.ID, 'f', 'm', 't', ' ');
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WriteLE32(&header.fmt.header.Size, kFmtSubchunkSize);
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WriteLE16(&header.fmt.AudioFormat, format);
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WriteLE16(&header.fmt.NumChannels, static_cast<uint16_t>(num_channels));
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WriteLE32(&header.fmt.SampleRate, sample_rate);
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WriteLE32(&header.fmt.ByteRate, ByteRate(num_channels, sample_rate,
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bytes_per_sample));
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WriteLE16(&header.fmt.BlockAlign, BlockAlign(num_channels, bytes_per_sample));
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WriteLE16(&header.fmt.BitsPerSample,
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static_cast<uint16_t>(8 * bytes_per_sample));
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WriteFourCC(&header.data.header.ID, 'd', 'a', 't', 'a');
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WriteLE32(&header.data.header.Size, static_cast<uint32_t>(bytes_in_payload));
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// Do an extra copy rather than writing everything to buf directly, since buf
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// might not be correctly aligned.
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memcpy(buf, &header, kWavHeaderSize);
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}
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bool ReadWavHeader(ReadableWav* readable,
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size_t* num_channels,
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int* sample_rate,
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WavFormat* format,
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size_t* bytes_per_sample,
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size_t* num_samples) {
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WavHeader header;
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if (readable->Read(&header, kWavHeaderSize - sizeof(header.data)) !=
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kWavHeaderSize - sizeof(header.data))
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return false;
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const uint32_t fmt_size = ReadLE32(header.fmt.header.Size);
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if (fmt_size != kFmtSubchunkSize) {
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// There is an optional two-byte extension field permitted to be present
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// with PCM, but which must be zero.
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int16_t ext_size;
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if (kFmtSubchunkSize + sizeof(ext_size) != fmt_size)
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return false;
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if (readable->Read(&ext_size, sizeof(ext_size)) != sizeof(ext_size))
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return false;
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if (ext_size != 0)
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return false;
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}
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if (readable->Read(&header.data, sizeof(header.data)) != sizeof(header.data))
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return false;
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// Parse needed fields.
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*format = static_cast<WavFormat>(ReadLE16(header.fmt.AudioFormat));
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*num_channels = ReadLE16(header.fmt.NumChannels);
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*sample_rate = ReadLE32(header.fmt.SampleRate);
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*bytes_per_sample = ReadLE16(header.fmt.BitsPerSample) / 8;
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const size_t bytes_in_payload = ReadLE32(header.data.header.Size);
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if (*bytes_per_sample == 0)
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return false;
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*num_samples = bytes_in_payload / *bytes_per_sample;
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// Sanity check remaining fields.
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if (ReadFourCC(header.riff.header.ID) != "RIFF")
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return false;
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if (ReadFourCC(header.riff.Format) != "WAVE")
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return false;
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if (ReadFourCC(header.fmt.header.ID) != "fmt ")
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return false;
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if (ReadFourCC(header.data.header.ID) != "data")
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return false;
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if (ReadLE32(header.riff.header.Size) < RiffChunkSize(bytes_in_payload))
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return false;
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if (ReadLE32(header.fmt.ByteRate) !=
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ByteRate(*num_channels, *sample_rate, *bytes_per_sample))
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return false;
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if (ReadLE16(header.fmt.BlockAlign) !=
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BlockAlign(*num_channels, *bytes_per_sample))
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return false;
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return CheckWavParameters(*num_channels, *sample_rate, *format,
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*bytes_per_sample, *num_samples);
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}
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} // namespace webrtc
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